In a vacuum or vacuum pressure conveying system, a dry flowable material is introduced into the system for transport from one location to another. In one simple example, granular or pelletized resin may be moved from a barrel or other container to a vacuum hopper that feeds a molding press or an extrusion press. The resin storage container may be close to the press or it may be some distance away. In a simple installation of this kind, a pneumatic pickup probe or wand, connected to a vacuum or vacuum pressure conveyor conduit, may be utilized to introduce the dry flowable resin into the conduit for transport to the vacuum hopper. The pickup probe also regulates the flow of material into the vacuum conveyor, being arranged to provide an optimum ratio of material and air at the pickup point within the storage container for the resin. When optimum conditions are achieved, the vacuum conveyor system operates most efficiently and can attain a maximum conveying rate.
A substantial variety of different constructions have been used for the pickup probe or wand employed to introduce dry flowable resins and other such materials into vacuum conveying systems. In general, the known pneumatic pickup probes have tended to be relatively complex in construction and hence more costly than desirable. The probes have frequently included moving parts that may fall off and hence may be transported into the molding machine or other equipment being fed by the vacuum conveyor system, with results that are frequently quite undesirable. Pickup wands of the prior art have also exhibited considerable difficulty in achieving a satisfactory ratio of air to the material being transported, with the result that optimum operation of the vacuum conveying system is not achieved. Yet another difficulty of previously known pneumatic probes has been a tendency to rest on the surface of the granular material supply instead of continuously burrowing into that supply as is desirable for extended operation.